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Specialist Materials for Industry and Science

Offshore Substations

Offshore Substations

Substations provide the vital link between wind turbines and the electrical grid. As wind farms move further offshore, substations are positioned on purpose-built platforms which bring with them many challenges including transformer fire safety and the cost of maintenance.

Offshore transformer fires are difficult to combat and could result in the wind farm being shut down. Filling a system with MIDEL 7131 instead of mineral oil increases fire safety because MIDEL 7131 has a much higher fire point (>300°C) and a 100% fire safety record. Furthermore, by specifying MIDEL 7131 has proven possible to design significantly smaller offshore substations, without complicated transformer fire suppression.

In offshore substations a transformer's performance is just as important as its fire safety. If the transformer fails to withstand the corrosive atmosphere it will need to undergo expensive unplanned maintenance. Therefore, it is essential to specify a fluid such as MIDEL that is extremely robust, oxygen stable and proven to work.

In addition to reliability and fire safety, wind energy transformers should, by their very nature be environmentally sound. In this respect, mineral oil and silicone liquid cannot compare to MIDEL 7131 because it is readily biodegradable and non-water hazardous.

Benefits of MIDEL 7131 in Offshore Substation Transformers

Increased Fire Safety

High Performance

  • Good oxygen stability, suitable for use in free breathing or sealed systems
  • Robust and stable at high temperatures over long periods 
  • Allows for compact design
  • Greater moisture tolerance than mineral oil, silicone liquid and natural ester
  • Excellent reliability, reputation as the ‘fill and forget fluid'
  • Very low pour point (-56°C)
  • No corrosive sulphur - ASTM D1275 B and IEC 62535
  • Proven up to 433kV in power transformers

Greater Environmental Protection

  • Readily biodegradable according to OECD 301 and fully biodegradable according to IEC 61039
  • Non-toxic and not harmful to aquatic life
  • RoHS compliant

Excellent Customer Service

  • Multilingual commercial team
  • First-rate customer care
  • Continued technical support from the transformer fluid experts

For further information please visit our Documents or Contact Us.



  • Apiezon
  • Metrosil
  • Midel
  • Wolfmet

Products of M&I Materials Ltd.